Collagen-induced arthritis is a well-studied animal model of human rheumatoid arthritis. An autoimmune process evolves after immunization with heterologous type II collagen in an adjuvant that induces an inflammatory response. The nature of the inflammatory response induced may be as critical as the antigen used, for mouse strains that have been previously believed to be resistant to disease can become susceptible when the immunization protocol is modified. The long-term objectives of this application are to develop an independent program of research that leads to an improved understanding of the etiopathogenesis of inflammatory arthritis based on a clearer characterization of the inflammatory responses necessary for an autoimmune disease to develop. Initially, characterization of immunomodulatory Th2 cytokines in disease progression will be performed. IL-4 and IL-10 deficient mice will be immunized with type II collagen, and the development of arthritis will be monitored. The immune response to collagen will be studied as determined by cytokine and chemokine expression in the absence of endogenous IL-4 or IL-10. The T cell response to antigen resulting from different immunization protocols will also be studied, as differences in the T cell repertoire may be responsible for the presence or absence of disease. T cell receptor V3 gene usage as well as epitope specificity of collagen-reactive T cells will be determined. Levels of collagen-reactive antibodies and binding specificities will be determined to assess the effect on B cell reactivity. Finally, innate immune responses to these immunization protocols will be ascertained. The expression and function of toll-like receptors will be studied by flow cytometry and immunoblotting, and the ability to produce cytokines such as IL-12 and IL-18 under different immunization conditions will be determined. By better understanding unique inflammatory pathways that are required for the development of disease, specific immunotherapy strategies for the treatment of autoimmune processes such as rheumatoid arthritis may be designed.